Rihanna was a happy camper after her performance on “Saturday Night Live.” She stopped to sign autographs and pose for pictures with fans outside Meatpacking District eatery Abe & Arthur’s before heading inside for the after-party. She was joined by host Blake Lively, her “Gossip Girl” co-star and boyfriend Penn Badgley, “Gossip Girl” creator Josh Schwartz, and “SNL” stars Andy Samberg, Bill Hader and Fred Armisen. Chace Crawford joined Lively and Badgley downstairs at club SL for a nightcap.